1. Technical Field
Example embodiments of the present invention relate to apparatuses for transmitting and receiving for frequency division multiple access (FDMA), and more specifically to apparatuses for transmitting and receiving which can reduce inter-user interferences and make as many users as possible access to a communication system having limited capacity in the communication system to which multiple users can access simultaneously.
2. Related Art
The Long Term Evolution (LTE) and LTE-Advanced system, the current mobile communication systems, use an Orthogonal Frequency Division Multiple Access (OFDMA) as their downlink multiple access scheme, and use a Single Carrier Frequency Division Multiple Access (SC-FDMA) and a DFT spread OFDM (DFT-s-OFDM) as their uplink multiple access scheme.
The Single Carrier Frequency Division Multiple Access (SC-FDMA) is a multiple access scheme achieving a single carrier characteristic by additionally applying a DFT spreading technique to OFDMA. Generally, OFDMA has a shortcoming of high power consumption due to its high Peak-to-Average Power Ratio (PAPR). Battery-powered user terminals prefer multiple access schemes having low PAPR in order to reduce their power consumption. Although the SC-FDMA scheme is based on OFDMA, it has the single-carrier characteristic, and so it has lower PAPR as compared with that of OFDMA. In this reason, the Long-Term Evolution (LTE) and LTE-Advanced have adopted the SC-FDMA as their uplink multiple access scheme.
In implementations for the LTE, there is usually a restriction in size of DFT in order to reduce complexity of hardware. That is, a size of DFT is determined as being factorized into only prime numbers 2, 3, and 5. Therefore, there are restrictions in determining size of resource blocks (RB) allocated for uplink by a base station, and so scheduling performed by the base station also becomes complicated.